Impact of the ACTN3 and ALDH2 gene polymorphisms on skeletal muscle phenotypes in response to exercise and anabolic steroid use

• Grant number: 23/16360-8
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate (Direct)
• Start date: May 01, 2024
• End date: April 30, 2025
• Field of knowledge: Health Sciences - Physical Education
• Principal Investigator: Guilherme Giannini Artioli
• Grantee: Wagner Ribeiro Pereira
• Supervisor: Jane Seto
• Host Institution: Faculdade de Medicina (FM). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Institution abroad: Murdoch Children'S Research Institute, Australia
• Associated to the scholarship: 22/05145-6 - The role of aldehyde dehydrogenase 2 and reactive aldehydes on the anabolic responses, satellite cell activation and recovery from muscle damage in response to strength training: a study with ALDH2 gene mutation carriers, BP.DD

Abstract

Muscle strength and size are important components of overall health and quality of life. Several intrinsic biological factors are involved in the regulation of muscle mass and muscle growth, including genetic characteristics, satellite cell function and myonuclei content. ACTN3 R577X and ALDH2 Glu487Lys are two genetic polymorphisms that have been shown to influence skeletal muscle biology, thereby having implications for overall health as well as athletic performance. In sports context, several athletes often use ergogenic aids to maximise performance, however some of these consist of illegal and harmful substances, such as testosterone and its metabolites (e.g. dihydrotestosterone). Recently, a group of Australian researchers showed that the ACTN3 R577X gene polymorphism impacts how muscles respond to testosterone. Beyond this, evidence suggest that the use of testosterone and dihydrotestosterone (DHT) can lead to persistent long-term adaptations in the skeletal muscle even after long periods following treatment interruption (i.e., "muscle memory"). In this project, our aim is twofold: 1) to examine the long-term responses to DHT exposure in female mice skeletal muscle; 2) to complete a number of analyses in the samples collected as part of the proponent's PhD project that is currently in progress (FAPESP #2022/05145-6). Within aim 1, 32 C57BL/6 female mice, 50% wildtype (WT) and 50% ACTN3 knockout (KO) will be randomly assigned to be treated for 6 weeks with anabolic steroid (5±-dihydrotestosterone, DHT) or with a saline control solution (SHAM). Thus, four different groups will be formed, as follows: KO+DHT, KO+SHAM, WT+DHT, WT+SHAM. Upon treatment completion, a 3-week washout period will be given, then both groups will start an 8-week resistance exercise training protocol. At the end of training programme, all mice will be examined for grip strength, muscle contractile properties, and their skeletal muscle will be harvested for further analyses. Within aim 2, we will perform at the Murdoch Children's Research Institute (MCRI) part of the analyses in the skeletal muscle samples that have been proposed in the initial project funded by FAPESP. Skeletal muscle samples will be submitted to immunoblotting to analyse mechanotransduction pathways (AKT/mTOR), pathways that regulate satellite cells differentiation (WNT/²-catenin) and angiogenic signalling pathway (VEGF) as well as immunofluorescence to analyse satellite cells, myonuclei and muscle fibre capillarization.